As a large-scaled (or large-sized) video display apparatus for enlarging a display screen is already known and is widely utilized a projection-type video display apparatus, which projects a video upon a transmission-type projection surface, through a video projection unit for projecting, with using a video display element, such as, a liquid crystal panel, etc.
Conventionally, for example, in the following Patent Document 1 is already disclosed the structures, in which a mirror, for reflecting the video from the video projection unit thereon, is attached at a predetermined inclination angle, on an inner wall of a rear surface of a housing, standing a projection screen on a front surface, while storing the video projection unit in an inside thereof.
Also, in the following Patent Document 2 is already known a projection display apparatus, which does not need the mirror on a rear-surface side of the projection screen, and in that Patent Document is disclosed that for transmitting or reflecting a video light, being bright and high in contrast even in an oblique projection, in a predetermined direction, with applying a hologram therein.
Further, in the following Patent Document 3 is also already known a rear-surface projection type display apparatus, which reflects a video, so as to project upon the projection screen, by a mirror, being held upright similar to that screen, on a rear surface of the projection screen, while projecting the video on the projection screen, which is held upright in a front surface of the housing, with applying an oblique projection optic system.